An effort was made to develop a system which could utilize the principles of a polygraph, or “lie detector”, but would be remote and not require physical contact with the person to be tested. A key component of a polygraph is the measuring of the Galvanic Skin Response (GSR), also termed Electro-Dermal Activity (EDA) or Electro-Dermal Response (EDR), or Sympathetic Skin Response (SSR). For this application, the term EDR will be used to refer to this response. In a polygraph, the EDR is measured by placing an electrode on each of two finger tips such that the measurements provide an instantaneous measurement of skin conductance or its inverse, skin resistance. During a typical polygraph examination, the subject is instructed to remain perfectly still and answer “yes” or “no” to a series of planned and previously discussed questions. Changes in skin conductance/resistance immediately following relevant questions are used to determine the stress of deception during such polygraph examinations.
It is well known in the polygraph literature that if a small amount of electrical current is passed through the body, the electrical conductance/resistance of the skin can be measured. See Matte, James Allan, “Forensic Psychology Using the Polygraph,” J.A.M. Publications, Williamsville, N.Y., 1996, One of the primary functions of the polygraph is to measure the physiological activity that accompanies physiological stress reactions to telling a lie or of fear of being caught in a lie. See Vrij, Aldert, “Detecting Lies and Deceit,” John Wiley: West Sussex, 2008, p. 294. During a deceptive response, the resistance of the skin decreases, and conversely the conductance rises. It has been speculated that opening of the skin pores is related to an increased conductance of the skin. See Freedman, L. S., et al., “The Relationship of Sweat Gland Count to Electrodermal Activity,” Psychophysiology, 1994, 31(2): 196-200 and Juniper, K, Blanton, D. E. & Dykman, R. A., “Palmar Skin Resistance and Sweat-gland counts in Drug and Non-drug states, Psychophysiology, 4, 231-243 (1967). In each of these cases, however, the number of skin pores on the hand was related to the EDR on the finger tips in one instant in time. A sweat gland count was accomplished by painting the finger or palm with, for example, a solution of iodine and alcohol and making an imprint or counting the black sweat pores on the palm as showing sweat pores.
Other researchers have reported that the sweat response is a sensitive indicator of sympathetic activation during mental arithmetic and distressing films. See D. Yamashiro et al., “Sympathetic Skin Response and Emotional Changes of Visual Stimuli, No To Hattatsui. 2004 September: 36(5): 372-7 [Article in Japanese, only abstract translated]. One useful measure of palmar sodometer (perspiration) activity has been a Palmar Sweat Index (PSI), defined as a number of spots of sweat in a 4 mm2 skin region. T. Kohler et al., Z. Exp. Angew Psychol., 36(1): 89-100 (1989). The PSI was measured from plastic casts of the skin taken at 2.5 minute intervals. However, there was no way to observe the number of open pores in real time until the present invention.
The “fight or flight” reflex is a universal physiological response to threatening stimuli. See Cannon, Walter B., “Bodily Changes in Pain, Hunger, Fear and Rage: An Account of Recent Researches into the Function of Emotional Excitement,” Appleton, N.Y., 1915. The reflex occurs through the activation of the sympathetic nervous system and is accompanied by sudden and significant changes in the physiology of the body. Heart and breathing rate increase. Sweat glands prepare to cool the body. Pupils of the eyes dilate presumably to bring in more light to better see the threatening stimulus. This “fight or flight” reflex underlies the most significant component of the polygraph, the change in skin conductance that is associated with the threat of being caught in a lie or being discovered as the perpetrator of a crime and suffering the penalty of such discovery. This reflex is used in the polygraph to detect that a person is at the present moment under observation responding to a question that relates to involvement in a crime and lying during a polygraph examination.
All polygraph techniques essentially attempt to show a difference between responses to questions that are relevant to the particular crime in comparison with those that are not. A person guilty of a crime is presumably going to respond to a greater extent to relevant questions than an innocent person would or than to questions that are not relevant to a crime for which he could suffer punishment (jeopardy). There are several major techniques or formats for structuring the questions during a polygraph examination. These techniques fall into the following categories:                Control Questions Testing: Questions that would be non-threatening to an innocent person but threatening to a guilty person with respect to the particulars of the crime committed.        Relevant-Irrelevant: Questions that have a control lie question to compare with the particular relevant question(s) related to the crime.        Guilty Knowledge The suspect is asked several questions about the crime that includes details that only the crime investigators and the criminal would know about. If the suspect consistently shows the strongest emotional reaction to questions containing correct details, such responses would suggest that he is the criminal and possesses knowledge that only the criminal would have.        Peak of Tension Test: The Peak of Tension Test is similar to the Guilty Knowledge Test except that the details are asked in a certain order and the suspect can expect the detail to come in the question. As the interviewer reaches the detail of interest the person will tend to increase in conductance response.        The “Timely Reaction Rule” provides guidelines for determining whether a reaction is related in time to a particular question. Specifically, it states that the response (change in conductance) must occur following the first word of the question or if the response starts within five seconds of the answer being given.        
Lie detectors or polygraphs have been used for years to determine the truthfulness of a person's answers and as a result, the trustworthiness for employment. The polygraph requires an expert to give the test and interpret the results. It also requires that a person be willing to be tested and be connected to various electronic devices.
There are many situations within law enforcement, military, and intelligence scenarios in which it is highly advantageous and sought-after to determine whether a person is concealing knowledge or information about a crime, a terrorist act, or other such important event and its perpetrators. This determination can be improved when the person's physiological responses can be observed without physical contact with the subject. In a battlefield scenario, unlike a criminal event in law enforcement, the goal is not strictly to get a confession of guilt from a detainee or to determine whether the detainee has committed an actual act of terrorism or counterinsurgency. More importantly, it is often to find the network, the bomb maker, or other information that may be known to the subject. Similarly, when an event takes place, there may be many innocent civilians in the area who have information they are concealing to keep themselves or loved ones safe.
Within the United States, ever since the tragic intentional airplane crashes on Sep. 11, 2001, there has been an increased interest in identifying individuals flying within and into the United States, who may be dangerous and could cause serious harm to a significant number of American citizens and residents. Although individuals coming into the United States from a foreign country are required to have and show a passport, this does not indicate if they may be dangerous. However, if they are on a “no-fly” list, they may be subject to special procedures prior to being permitted to board a plane.
Persons boarding a plane usually have to go through a screening procedure where they are viewed by a Transportation Security Administration official and their carry-on luggage is scanned by a metal detector. People coming in from outside the United States go through customs where their luggage may be inspected and they may be asked a few general questions. If these individuals were concealing information about any imminent violent intentions with respect to the United States, it would be advantageous to be able to interview them effectively about their intentions.
Various systems have been developed to measure the emotional response of individuals remotely. One of these was by Ioannis Pavlidis who used a thermal camera to measure the change of blood flow in the subject's face, and particularly in the periorbital region and forehead. He obtained patents on this technology, including U.S. Pat. Nos. 6,854,879, 6,996,256, 7,111,980 and 7,138,905. These systems all require transforming the thermal image data to blood flow data.
John Newman also recognized that a person's skin temperature will increase because of anxiety and developed a system described in U.S. Pat. No. 6,837,615, which measures the differences in skin temperature in the face and neck.
Finally, Francine Prokoski disclosed in U.S. Pat. No. 7,027,621 an embodiment of an invention for screening interviewees and applicants to detect possible deception using a thermal camera focused on the face of the interviewee or applicant to detect and monitor thermal variations.